Solid waste which includes construction refuse and the like is sorted into different classes of material with the aim of environmental conservation by recovering and reusing recyclable materials. This sorting is carried out by waste processing plants equipped with solid waste sorting systems, and the following kinds of problem have been associated with the waste sorting system processes:
(1) Sorting is carried out both by hand and using various sorting machines such as vibration sifting machines, bucket screen machines, and incline sorting machines.
Although relatively large items such as large pieces of metal, corrugated cardboard, and waste plastic can be picked out by hand, small items, cannot be. Furthermore, small items cannot be sorted by bucket screen or incline sorting machines either.
Although vibration sifting machines can be used to separate out small pieces of waste, this too is unsatisfactory because pieces are separated out based only upon their maximum dimension. Sorting dimensionally is not effective, for example, in separating out chips of wood, or pieces of paper or plastic or the like, when mixed up with gravel and lumps of soil and cement.
(2) Solid waste sorting systems are provided with belt conveyors for transporting the solid waste, and the solid waste is sorted by hand as It moves along the conveyors.
However, when the solid waste is piled deeply on the belt conveyors, manual sorting is encumbered. On the other hand, if the solid waste is loaded thinly on the belt conveyors in order to facilitate manual sorting, the throughput rate at which the waste can be processed is reduced.
(3) Only one belt conveyor is provided next to the solid waste storage area; solid waste cannot be transported into the processing plant at a high throughput rate by just one belt conveyor. If the rate at which solid waste is transported into the plant cannot be Increased, the rate at which the waste is sorted cannot be increased.